/*
 * Copyright (C) 2020 Baidu, Inc. All Rights Reserved.
 */
package com.jdk.io.io多路复用nio;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;
/**
 * NIO客户端
 * @author yangtao__anxpp.com
 * @version 1.0
 */
public class ClientHandle implements Runnable{
	private String host;
	private int port;
	private Selector selector;
	private SocketChannel socketChannel;
	private volatile boolean started;
 
	public ClientHandle(String ip,int port) {
		this.host = ip;
		this.port = port;
		try{
			//创建选择器
			selector = Selector.open();
			//打开监听通道
			socketChannel = SocketChannel.open();
			//如果为 true，则此通道将被置于阻塞模式；如果为 false，则此通道将被置于非阻塞模式
			socketChannel.configureBlocking(false);//开启非阻塞模式
			started = true;
		}catch(IOException e){
			e.printStackTrace();
			System.exit(1);
		}
	}
	public void stop(){
		started = false;
	}
	@Override
	public void run() {
		try{
			doConnect();
		}catch(IOException e){
			e.printStackTrace();
			System.exit(1);
		}
		//循环遍历selector
		while(started){
			try{
				//无论是否有读写事件发生，selector每隔1s被唤醒一次
				selector.select(1000);
				//阻塞,只有当至少一个注册的事件发生的时候才会继续.
//				selector.select();
				Set<SelectionKey> keys = selector.selectedKeys();
				Iterator<SelectionKey> it = keys.iterator();
				SelectionKey key = null;
				while(it.hasNext()){
					key = it.next();
					it.remove();
					try{
						handleInput(key);
					}catch(Exception e){
						if(key != null){
							key.cancel();
							if(key.channel() != null){
								key.channel().close();
							}
						}
					}
				}
			}catch(Exception e){
				e.printStackTrace();
				System.exit(1);
			}
		}
		//selector关闭后会自动释放里面管理的资源
		if(selector != null) {
			try{
				selector.close();
			}catch (Exception e) {
				e.printStackTrace();
			}
		}
	}
	private void handleInput(SelectionKey key) throws IOException{
		if(key.isValid()){
			SocketChannel sc = (SocketChannel) key.channel();
			if(key.isConnectable()){
				if(sc.finishConnect()) {
					;
				} else {
					System.exit(1);
				}
			}
			//读消息
			if(key.isReadable()){
				//创建ByteBuffer，并开辟一个1M的缓冲区
				ByteBuffer buffer = ByteBuffer.allocate(1024);
				//读取请求码流，返回读取到的字节数
				int readBytes = sc.read(buffer);
				//读取到字节，对字节进行编解码
				if(readBytes>0){
					//将缓冲区当前的limit设置为position=0，用于后续对缓冲区的读取操作
					buffer.flip();
					//根据缓冲区可读字节数创建字节数组
					byte[] bytes = new byte[buffer.remaining()];
					//将缓冲区可读字节数组复制到新建的数组中
					buffer.get(bytes);
					String result = new String(bytes,"UTF-8");
					System.out.println("客户端收到消息：" + result);
				}
				//没有读取到字节 忽略
//				else if(readBytes==0);
				//链路已经关闭，释放资源
				else if(readBytes<0){
					key.cancel();
					sc.close();
				}
			}
		}
	}
	//异步发送消息
	private void doWrite(SocketChannel channel,String request) throws IOException{
		//将消息编码为字节数组
		byte[] bytes = request.getBytes();
		//根据数组容量创建ByteBuffer
		ByteBuffer writeBuffer = ByteBuffer.allocate(bytes.length);
		//将字节数组复制到缓冲区
		writeBuffer.put(bytes);
		//flip操作
		writeBuffer.flip();
		//发送缓冲区的字节数组
		channel.write(writeBuffer);
		//****此处不含处理“写半包”的代码
	}
	private void doConnect() throws IOException{
		if(socketChannel.connect(new InetSocketAddress(host,port))) {
			;
		} else {
			socketChannel.register(selector, SelectionKey.OP_CONNECT);
		}
	}
	public void sendMsg(String msg) throws Exception{
		socketChannel.register(selector, SelectionKey.OP_READ);
		doWrite(socketChannel, msg);
	}
}